DNS uses port 53 for both TCP and UDP to serve its purpose of translating human-friendly domain names like 'example.com' into IP addresses that computers use to identify each other on the network. While DNS queries are generally sent using UDP to save on resources due to their small size and need for quick responses, TCP is used for larger queries like zone transfers or when reliability is of more concern over the slight delay that establishing a TCP connection brings. The other ports mentioned serve different protocols entirely (FTP and HTTP) and are not primarily associated with DNS activity.